Limitations in mobility affect almost one in 4 individuals over 65 and have been demonstrated to be predictive of disability and institutionalization. In those most limited, muscular power, the ability to perform muscular work per unit time, is closely associated with the functional tasks that predict disability. Muscular power is a separate attribute from strength declining more precipitously in late life. The preservation of muscular power in late life has been recently identified as high priority for gerontological research. The candidate in this application is a physiatrist, a clinician researcher with a Masters in Exercise Physiology, who specializes in geriatric rehabilitation. It is the applicant's goal to evaluate the influence of eight Vest Exercise a form of muscle power training (MPT) on functional loss in mobility limited elders. Through pilot studies in elders with mobility limitations, the applicant and his collaborators have demonstrated the close relationship between lower extremity muscular power and important tasks of functional performance. Additionally, pilot studies have shown that MPT is not only safe, but also more potent than strength training at correcting lower extremity motor impairments. Lastly, the applicant is investigating the potential of Weighted Vest Exercise, having preliminary results demonstrating its effectiveness. This award is framed around the following activities: 1) conducting a pilot intervention trial utilizing weighted vest exercise, a potential home-based type of MPT in elders with significant mobility limitations; 2) enhance my career development plan through continued involvement as co-investigator in an RO1 studying closely related issues; 3) completing studies in clinical trial methodology and utilizing these previous experiences as the basis for a randomized controlled trial, that is appropriately powered to evaluate the influence of non-machine based MPT on all disablement outcomes, including disability; and 4) develop the skills, expertise and experience to become a successful independent clinician scientist within the field of geriatric rehabilitation. This proposal contains a strong environment and mentorship plan containing leading institutions and individuals from the fields of Aging and Rehabilitation. It will provide important insights into exercise's role in preserving late life functioning.